Bariatric surgery increases fertility rates but study conclusions recommend postponing pregnancy until weight loss has stabilised and vitamin status normalised. Regular monitoring of vitamin status and vitamin supplementation is thus also recommended.
With an emphatic message, the authors of a new systematic review and meta-analysis into the impact of bariatric surgery on women’s periconceptional health – the first to focus specifically on the time before and after conception – advise postponing pregnancy until vitamin levels stabilise, irrespective of the interval between surgery and pregnancy.(1)
The recommendations are prompted by their finding that invasive weight loss procedures are associated with vitamin deficiencies among patients. Surgery-related malnutrition is a ‘compelling reason’, they say, to advise a delay ‘until a return to or maintenance of physiological vitamin concentrations’. On this question, the authors highlight a need for worldwide guidelines on (vitamin) supplementation before and during pregnancy for women who’ve undergone bariatric surgery for weight loss.
With all that said, the authors of this meta-analysis - from the Erasmus University Medical Centre in Rotterdam -first conclude that different types of bariatric surgery are indeed associated with significantly improved fertility and restored menstrual cycle regularity, a reassuring and positive outcome for women desiring motherhood who have had or are considering such procedures. What’s more, the results showed no increased short-term risks for miscarriage or birth defects.
A third (34%) of women of reproductive age are classed as obese, and the implications of this for their pregnancy chances are well documented. For very overweight patients who do conceive, outcomes are poor (higher risks of preterm birth and pre-eclampsia), and increased risks in offspring of obesity and hence cardiovascular diseases later in life.
Extensively used by health services, bariatric surgery is considered the most effective – indeed the only – long-term solution for weight loss in patients with a BMI of 40 or above. On the other hand, it’s not a magic bullet: the rapid and excessive weight loss from such interventions can result in malnutrition by inhibiting vitamin and mineral absorption with consequences for the mother-to-be and developing fetus.
There have been several systematic reviews on bariatric surgery and women’s reproductive health. The most recent did highlight the increased risk of micronutrient deficiencies.(2) However, the focus overall has been on pregnancy complications, not on maternal health in the periconception period alone, which was the aim of this latest analysis.
The findings were based on a review of 51 study reports published up to 1 November 2020 on women undergoing all types of weight loss surgery. The focus was the effect on health during periconception, defined by the authors as 14 weeks before conception until 10 weeks after. Of the studies analysed, six addressed malabsorptive procedures (eg, biliopancreatic diversion), 11 restrictive (eg, sleeve gastrectomy), and 37 investigated combined surgeries (eg, gastric bypass) or did not specify the surgery type.
Topics included endocrine changes post surgery, fertility, vitamin status preconception and in the first trimester, irregular menstrual cycles, and miscarriage prevalence in the first trimester. Congenital malformations were also included because most start within the first 10 weeks of fetal development. Excluded were articles that only included PCOS patients on the basis that the hormone condition may influence the associations between bariatric surgery and outcomes.
The results found that both fat and water-soluble vitamin deficiencies ‘occurred regularly’ after bariatric surgery and independent of the type of procedure (eg, vitamin B12 decreased in the first trimester of pregnancy). Yet no short-term risks were identified for reproductive periconception outcomes, such as increased miscarriage (a risk difference of zero) or congenital malformations (RD 0.01). Before and after (surgery) studies showed hormonal serum levels normalised, and menstrual cycles became more regular with an associated decrease in infertility (eg, more natural conceptions and better ART results). A separate meta-analysis of 20 studies confirmed this: infertility decreased significantly (risk difference 0.24) and menstrual cycle irregularities improved (RD 0.24), with no association found between bariatric surgery and congenital malformations and miscarriage rate.
So how do the authors explain the restoration of fertility? The return of menstrual cycle regularity leading to natural conception - which in turn improves pregnancy outcomes - is one possible suggestion. A note of caution is sounded here – that surgery should lead to ‘sufficient weight loss’ to restore menstrual cycle. Temporary procedures (eg, adjustable gastric banding) are therefore not recommended.
Many of the studies analysed by this review did not report outcomes per type of bariatric surgery separately. It’s essential that future research provides this evidence, according to the authors, because of ‘considerably differing mechanisms and anatomical and physiological consequences’. In addition, there is work to be done on the long-term impacts of bariatric surgery on women’s health, such as whether associated endocrine changes could influence the age of menopause.
1. Snoek K, Steegers-Theunissen R, Hazebroek E, et al. The effects of bariatric surgery on periconception maternal health: a systematic review and meta-analysis. Hum Reprod Update 2021; doi:10.1093/humupd/dmab022
2. Shawe J, Ceulemans D, Akhter Z, et al. Pregnancy after bariatric surgery: consensus recommendations for periconception, antenatal and postnatal care. Obes Rev 2019; 20; 1507–1522; doi/10.1111/obr.12927